Preservation of milk products



Dec. 10, 1946.' ;v BRUNKHURST 2,412,203

PRESERVATION OF MILK PRODUCTS Filed April 27. 1945 FIL 75x50 me fg 55 nrrmP/vfr Patented Dee. 1o, 194e 1 UNITED STATES PATENT IOFFICE- I 'l I 2,412,203" 5 V gansaavs'noiv or MILK raonuc'rs Y charles'mnknmt, Mid'dietnwn, N. Y. Application April 27, 1943, Serial No. 484,716

. At the `present time, the common practices for obtaining a reconstituted whole milk are to add water to preserved evaporated whole milk or to milk powder. Such reconstituted whole milk is generally unsatisfactory. Either the vreconstituted milk has a poor appearancev or it lacks flavor, generally both: Attempts have been/made to improve the quality of the reconstituted whole milk either by freezing fresh whole milk in its original state or by freezing evaporated milk. Freezing of the fresh whole milk,y in its original diffused form to quick freezing to freeze the mixture whence it may be formed into frozen cakes for shipment to the trade in the same manner as any frozen food product. The cakes may be formed in suitable size to which the consumer adds water to form the reconstituted whole milk.

The invention also consists in certain new and original features and' combinations `hereinafter set forth and claimed. v

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims 'appended hereto, the invention itself, as to. its objects and advantages, andthe manner'in which it may be carried out, may be better understood by refer-- 2 ring to the following description taken in con nection with the accompanying drawing forming ess; and

state is, of course, open to the additional objecter-air blow type of concentrator suitable for tion of having too much bulk for storagepurpracticing the invention. poses. In all .cases the Whole milk available In the following description and in the claims, for drinking is defetive in both appearance and various details will be identified by specific names f taste. Either the fats and solids separate\out, for convenience, but they are intendedy to be as or the'milk has a brownish ,color, or it has a flat, 20 generic inftheir application as the art will permit. tinny, caramel, burnt or other'unpleasant taste. In the drawing accompanying and forming An important feature of the present invention part of this specification, certain specific dis- -is the manufacture of a frozen concentrated i closure ofthe invention is madefor purposes whole milkl product which, when water is added. of explanation, but it willbe understood that the Y will be so like the originel fresh Whole milk in details may bemodined in various respect without r consistency, appearance and taste thatl it would departure from the broad aspect of the invenbe difficult, if not impossible, for anyone to tell ,i tion. the difference. Y Referring now to the drawing, the apparatus According to a preferred embodiment of the for carrying out the quick freezing step will first invention, the whole unpasteurized milk, as it is be described. In Fig. 1 a pair of rotating horiqbtained from the farmer, is subjected to a cream zontal hollow cylinders Ill and i-l are rotatably separating process for separating the cream from mounted, these cylinders having smooth surfaces the skim milk. The skim milk is then suitably and being in direct contact. They are suitably concentrated in a hot water-air blow type congeared together and rotated in the direction of centrator to reduce the` water content'. ,The 35 the arrows. The apparatus illustrated-in Fig. 1 cream is separately pasteurized, after which the is similar in principle to machines now on the a concentrated skim milk and cream is re-mixed. market, known as "Flake-Ice or"Pak-Ice, used The mixture is then homogenized, while/hot, to for making artificial ice. Scrapers i3 and i4 break up the fats and solids, to insure .thorough 'engage the drums to scrape off the mix freezing emulsiilcation. The mixture is then subjected in 40 on the drums, the mix being fed through pipe I2 as indicated. ...s Referring now to Fig. 2, a batch-type quick /ireezing apparatus is diagrammatically illusmg a suitable cooling jacket 2|.

circulated through the jacket 2I inthe direction of the arrowsthrough pipes 29 and 30, as will be understood by those skilled in the art.

Referring now to Fig. 3, a continuous type quick freezing apparatus is shown diagrammatically. 'I'his device comprises concentric tubes, the inner tube being indicated by 40 and the outer tube by 4I. A refrigerating jacket 42 surrounds the outer tube. The space between tubes 40 and 4I communicates with a feed hopper 43 having 'a removable cover and havinga pipe 44 connected to a suitable source of compressed air (not shown). The space between tubes` 40 and 4I also communicates with a discharge conduit 45 discharging into a receptacle 48. A branched feed pipe 41 supplies refrigerant, such as brineor ammonia, to the jacket 42 and to the inside of pipe 40v and a branched outlet pipe 48 carries away the refrigerant, as will be understood by those skilled' in the art.

Referring to Fig. 4, the structure of the preferred concentrator will now be described. The g hot Water-air blow type concentrator comprises an open top tank 60 having a suitable water jacket 6I. 'Ihe skim milk is fed into tank 80 from a suitable container 59 through Vsupply pipe 62. The level of the skim milk is kept at level indicated by 63 by supplying additional skim milk as the water is evaporated. The milk level isvobserved by a glass 54. The concentrated skim milk is drawn off through outlet pipe 55.

Disposed within tank 80 is an air pipe 56 to which is connected a supply of filtered air generated by a suitable blower. The air pipe 56 opens up near the bottom of the tank so that air is blown into the bottom of the liquid suitably agitating the liquid and bubbling through it, escap'l ing from the open top of the vessel.

Also located in the tank 60 is a hot water coil 51 having an inlet pipe 58 and outlet pipe 64. Inletl pipe 58 issbplied with hot water by a pump 50 receiving Water from a hot water heater 5I. Outlet pipe 64 leads back to the hot water heater. A connection 52 connects inlet pipe 58 with the water jacket 6I and a connection 53 connects the f water jacket 6I with outletpipe 54.

The hot water and milk pass through the pipes as indicated by the arrows. Hot water is circulated through the ,hot water coil 51 and through the water jacket 8| to keep the milk in the tank at the proper temperature, but without overheat- -ing it.

The process for preserving wholemilk will now be described. The cold fresh whole milk, as it is obtained from the farmer, is first fed to a suitable cream separator for separating the wholemilk into cream and skim milk. It is desirable to produce a. cream having 40% butterfat ,by weight. This removes substantially all the but. terfatfrom the milk. The creanr is then transferred to a cream storage vat where itis pasteurized by any suitable pasteuri'zing process, The skim milk, from which substantially allthe but-A terfat has been removed, is separately taken to any concentrating device for reducing, but not eliminating, the water content. The yconcentrationis,y carried on preferably by a hot water-air blowA concentrator shown in Fig. 4 where the skim milkisflsubjected to elevated temperature without cooking'v it. o

Referring now to Fig. 4, the skim milk is led t'o vtank 59 and thence to the hot water-air blow concentrator 60 through inlet pipe 82. The temperature of the hot water flowing through the jacket BI and through coil "should not exceed about 170 F. so that the milk contacting the walls of the jacket and the hot water coil 51 w` not become scorched or cooked. At the same time illtered air is fed into the concentrator through supply pipe 56 to impart turbulence to the milk and to evaporate water from the milk. Skim milk is added` to concentrator 60 from time to time to maintain-the liquid level at 63 to compensate for evaporation.

The apparatus is so designed and the method so conducted that the temperature of the milk'in the concentrator 60 will rbe about 143 F. and the milk is held at this temperature for at least thirty minutes so that pasteurization is obtained at the same time the water content is being reduced.

The concentrated hot skim milk and hot cream, in the same relative proportions as they occurred in whole milk, are then re-mixed in' a suitable l After the emulsifying operation, the hot concentrated homogenized milk, which may be at substantially 143 F., is fed directly to a' quick freezing apparatus, as for example, into the pipe I2 in Fig. 1, the hopper 25 in Fig. 2, or the hopper 43 in Fig. 3. Or, the hot homogenized milk may be first cooled to rooml or tap water temperatures before subjecting'it to the quick freezing operation in the above machines. In the event the hot milk is rst cooled before subjecting to quick freezing, it is preferable that it then be fed to the quick freezing apparatus after cooling without undue delay since if the hot milk is cooled to below about 100 F. and allowed to stand, there` `is a tendency for the milk sugar to crystallize,

forming undesirable large crystals.

In Fig. l1, the concentrated milk and cream is fed through a pipe I2 into the space between the cylinders as indicated, this mix being spread upon 'the cylinders in a thin layer and carried around as they rotate. Suitable refrigeration is applied inside the rotating drums I0 and II and the entire process may be carried out in a refrigerated room. 'I'he liquid milk quickly freezesv in a thinS layer on the surface of the drums where lt is scraped oil by scrapers I4 and I3, the scraped milk snow being collected by any desirable'apparatus and compressed into cakes.

f In Fig. 2, the batch of concentrated milk and cream is fed into the hopper -25 to charge the cylinder 20, after which feed valve I8 is closed. The scraper blades 23 continually expose the 'dif ferent parts of the mix to the cold refrigerated walls until the entire mix is frozen to the proper consistency. The overrun normally present whe'n freezing ordinary icecream is considerably reduced by minimizing the whipping action, by the 65 omission of swelling agents and by freezing a litcrystal `growth takes place in the hardening room.

" perature.

'In Fig. 3 the concentrated milk and cream is fedinto the feed hopper and sufficient compressed air is supplied to pipe 44 to insure/fan even flow of the mix through the machine. 'Ihe passage of the mix between pipes 46 and Il in a very thin layer of say one-quarter inch in thickness quickly freezes the mix under pressure. The

material 4falls into a suitable container 46. The f container 46 may then be taken to a hardening room for further hardening under reduced tem- Due to the fine texture of the material, no further change in crystal structure takes place in the hardening room.

The quick freezing process spreads the concentrated mix into a large area subjecting small unit quantities to very low refrigerating temper- .atures The temperature of the refrigerating apparatus may be as low as -'40 F. to insure quick freezing of the product. 'I'he milk snow obtained from the apparatus of Fig. 1 may be in the form of a thin loose, frozen, dry powder. This may then be suitably compressed into cakes or bars. 'Ihe frozen product obtained from the machines of Figs. 2 and 3, after being subjected to the cold room, may be suitably cut into cakes or bars of the suitable size.'

The preferred temperature for pasteurizing the milk and cream is around 143 F. which is regarded as a good pasteurizing temperature. However, in some cases, the pasteurizing temperatures may run from as low as 140 F. to as high as 165r.

The temperature of the quick freezing apparatus should be as low asl-40 F. to insure the product being frozen with sufcient speed. It is desirable that the product quickly attain a temperature at least as low as '-10 F., although in some cases it may be desirable to have the product quickly reach a somewhat lower temperature. In other cases, it may be suilicient for the temperature to reach zero F. quickly.

The cakes or -bars may be of any standard size,

, depending upon the consumer demand. For example, the cakes or bars may be of such size that, when mixed with a predetermined amount of water, they will produce a half pint, pint, quart, gallon, etc. The cakes or bars may be formed in comparatively large sizes suitably grooved or divided so that parts of the desired size may be conveniently broken off.

' The amount of water to be added by the consumer depends upon the amount of concentration in the concentrating step and may vary considerably. It should be borne in mind that the more water eliminated in the concentration step, the more water will naturally have to be replaced by the consumer to get a true reconstituted whole milk. The amount of -water eliminated will depend upon commercial considerations.

In practice, the amount ofI concentration of skim milk may run from a ratio as small as 21/2 to l to a ratio as high as 4 to 1. The concentration ratio is defined as the ratio by volume of a given amount of skim milk before concentration to the volume occupied by that milk after concentration.

In reconstituting the milk, it is desirable, for

simplicity, that the proportions of `water to Lbe.

added to the frozen product be whole numbers and not fractions. For example, it is desirable that the concentration be such that it l is only necessary for the consumer to add, say, two partsof water by volume for each part by volume of frozen product. To obtain a frozen product requiring such a proportional addition of water, it is necessary that the concentration ratio 'of skim milk be approximately 3.86 to l.- This ratio is based upon a whole milk testing approximately 3.8% fat by'weight and allows for change in volume of the frozen product due to freezing and compressing. l

Consider for example a run of 360 quarts (9 cans) of whole milk containing 3.8% butterfat content by weight. This quantity of such milk contains about 29.05 lbs. ofy butterft or about so quarts. subtracting the 36 quarts of cream from the 360 quarts of whole milk, we have 324 quarts of skim milk. Concentrating the skim milk in a ratio of 3.86 to 1 gives about 84 quarts of concentrated skim milk. Adding the 36 quarts of cream and the 84 quarts of concentrated skim milk, we have 120 quarts of mixed milk and cream to Ibe subjected to the homogenizing and quick freezing -process above described. It will be noted that of frozen product. Or, the' frozen products may indicate the amount in liquid measure of reconstituted whole milk which can be made from the particular bar or part thereof so that it 1s only necessary for the consumer to place a cake or part thereof in a container of the indicated liquid measure and fill with water. f

It will be understood that the frozen product may be compressed in any desirableshape and shipped in any desirable container. For example, the frozen product may be shipped in small cartons of convenient size to fit into the freezing compartment of a household mechanical refrigerator. It is obvious also that the consumer may add anylesser amount of water than that neces'- sary to provide reconstituted whole milk and obtain a heavier product corresponding, vfor example, to fresh condensed milk or whipping or coflee cream.

- Thus, there -is` provided a preserved milk in frozen, concentrated, form which, when mixed with water, forms a reconstituted whole milk which has'all the avor, body, appearance, conhot water-air blast type of concentrator, no part of which has a temperature highery than F.. prevents cooking or `scalding the skim milk even briefly and thus does not caramelize any of the milk sugar or boil any of the proteins.

The homogenizing of the milk and cream while hot thoroughly breaks up thefats and solids into extremely ne particles and the solid particles` become encased in fat, which prevents any change in their form, so that on dissolving in water, the solids stay in suspension readily and there is no atrasos tendencyto form nne cuds.' or for the fat to clump. i

,The immediate cooling of the homogenized mixture to room temperature and the immediate' Ifreezing prevents the milk 'from thickening and The quick the milk sugar from crystallizing. l freezing ofthe homogenized product prevents the growth of large crystals so that, when the` frozen product dissolves, it mixes readilywith the Water,

" forming a good colloidal suspensionhaving appearance and taste entirely like the original whole milk.

' minutesto pasteurize the skim milk and to reduce the Water content to le'ss than one-half by volume, remixing the pasteurized cream and conf cent1-ated skim milk, homogenizing the hot milk Thus a method of preserving milk products.

- has been described which preserves the product without affecting the flavor or digestability. Due tothe elimination of; roughly, two-thirds of the water, great savingA in, space and weight is eiected, which is important for transportation and storage.` Due to the fact that the product is frozen, inexpensive containers, such as waxedl cartons may be used. Due to the wide distributionand sale of ordinary frozen food products, the frozen milk products can be distributed afnd sold without difficulty since the same distributing apparatus and technique may be used for the frozen milk products, as with other frozen food products now on the market.

Whilecertain novel features of the invention have been disclosed and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without. departing from the spirit of the invention.

What is claimed is: l 1. The method of making a'frozen whole milk product from which a reconstituted whole milk may be made by adding water, said method comprising separating fresh whole milk intovcr/eam 'and skim milk, subjecting the cream to a sutilciently high temperature to'pasteurize it without removing volatile matter, subjecting the skimy mixture to breakup the fats and solids and to cause the' solid particles to become encased in fat,4 immediately reducing the temperature of the homogenized mixture to tap water or normal room temperature, `quick-freezing the mixture without further delay to obtain a frozen concentrated whole milk, and forming said frozen concentrated whole milk into shapes.

3. The method of making a frozen whole milk product from which a reconstituted whole milk may be made by adding water, said method comprising separating fresh whole milk into cream and skim milk to produce a cream of about 40% butterfat content by weight, separately pasteurizthe hot milk mixture to break up the fats and homogenized mixture from above about 100 FJ milk to pasteurizing temperature to reduce thewater content in a concentration ratio by volume of between 21/2 to l and 4 to 1, homogenizing theA hot concentrated milk and cream together to break up the solids, reducing the temperature of the homogenized mixture to' normal room on tap f and skim milk, separately ,pasteurizi'ng the'cream,

Isolids and to cause the solid particles to become to normall room or tap water temperature without delay, -quick-freezing the mixture without furtherY delay to quickly bring the mixtureto a temperature of between zero and minus 40 F.

to obtain a frozen concentrated whole milk, and forming said frozen concentrated whole milk into shapes.

4. The'inethod of making a frozen whole milk product from whlch'a reconstituted whole milk may be obtained by adding water, said method water temperature and subjecting the mixture comprising separating fresh whole milk into cream and skim milk, pasteurizing the cream, separately concentrating the skim milk to re)- duce substantially the water content,` mixing the said pasteurized separated cream and said contrated separated skim milk, homogenizing the re-mixed milk, and quick-freezing the re-mixed homogenized milk to form the frozen whole milk product. y

, CHARLES BRUNKHURST. 

